The marketplace for internal combustion engines continues to move toward “alternative” fuels such as E15, E85, Ethanol and ultra-low sulfur gasoline, “greener” engines having lower fuel consumption, lower emissions and specifying composition of exhaust stream, and “greener” fuels (specifying composition of fuels, (i.e. low sulfur), composition of exhaust stream, . . . ). As such, Liquefied Petroleum Gas (LPG), which has been used for decades as a fuel source for fork lifts and some truck applications, is becoming a more widely used fuel for internal combustion, particularly for automotive internal combustion applications.
Automotive manufactures are keenly aware of performance, cost and reliability considerations relating to components or systems which may enter widespread field service and have an expected service life of years to decades. Fuel injectors for gasoline automotive applications have been in widespread deployment for about 20 years while widespread deployment of LPG fuel injector could be just over the horizon.
LPG is typically delivered into an intake manifold as a liquid. As such, if the LPG volatilizes into a gas prior to passage through the fuel injector, the engine could run “lean” (starving for fuel or excessive oxygen condition), providing less than optimal engine performance (power, emissions, possible engine damage). Fuel injectors designed for gasoline are not directly vented for volatilized fuel because gasoline inherently has a lower tendency to volatilize during normal operating conditions. With this in mind, LPG fuel injectors must have a vent/return port to return volatilized fuel to the fuel storage tank via a vent/return port.
A key consideration for component cost is in the design and development costs. Modularizing a component has important advantages in borrowing key design, development, manufacturing and supplier base. Modularizing allows elements of life cycle cost such as design, development, manufacturing, maintenance, replacement and disposal to be well understood and contained. LPG fuel injectors could benefit from modularity by borrowing elements from high-production gasoline fuel injectors.
Another consideration is component reliability. As internal components are exposed to fuel of an injector, there could be component degradation over time. Some LPG injectors have O-rings and electrical components such as the actuator coil exposed to fuel. Eliminating this with hermetic welds could improve the reliability of the fuel injector.
It would therefore be desirable to provide a LPG fuel injector with high performance, low cost and high reliability.